Lawyers for the United States on Monday said that Google had created a monopoly with its services to place ads online, closing out an antitrust trial over the company’s dominance in advertising technology that could add to the Silicon Valley giant’s mounting woes. From a report: The legal case concerns a system of software that is used by advertisers to place ads on websites around the internet. Aaron Teitelbaum, a lawyer for the Justice Department, told Judge Leonie M. Brinkema of the U.S. District Court for the Eastern District of Virginia that the company had linked its products together in a way that made it hard for publishers and advertisers to use alternatives.

“Google is once, twice, three times a monopolist,” he said. “These are the markets that make the free and open internet possible.” Google’s lead lawyer, Karen Dunn, countered that the government had failed to offer the evidence to prove its case and was on shaky legal ground. “Google’s conduct is a story of innovation in response to competition,” she said. The arguments conclude U.S. et al. v. Google, an antitrust suit that the Justice Department and eight states filed against Google last year. (More states have joined the suit since then.) The agency and states accused the internet giant of abusing control of its ad technology and violating antitrust law, in part through the acquisition of the advertising software company Doubleclick in 2008. Next, Judge Brinkema will decide the merits of the case in the coming months.